Short-Term and Long-Term Investments (Details) - USD ($) $ in Thousands	Oct. 31, 2018	Aug. 30, 2018	Oct. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Debt conversion liability	$ 164,212	$ 152,100	$ 0
Amortized Cost	208,357
Estimated Fair Value	207,951
U.S. government obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	198,394		299,408
Gross Unrealized Gains	0		0
Gross Unrealized Losses	(406)		(432)
Estimated Fair Value	197,988		298,976
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,963		29,939
Gross Unrealized Gains	0		1
Gross Unrealized Losses	0		0
Estimated Fair Value	9,963		29,940
Short-term Investments \| U.S. government obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	139,365		249,498
Gross Unrealized Gains	0		0
Gross Unrealized Losses	(347)		(305)
Estimated Fair Value	139,018		249,193
Short-term Investments \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,963		29,939
Gross Unrealized Gains	0		1
Gross Unrealized Losses	0		0
Estimated Fair Value	9,963		29,940
Other Long-term Investments \| U.S. government obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	59,029		49,910
Gross Unrealized Gains	0		0
Gross Unrealized Losses	(59)		(127)
Estimated Fair Value	$ 58,970		$ 49,783

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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